The availability and widespread adoption of mobile computing devices, such as smartphones, tablet computers, mobile data entry terminals etc. has increased significantly recently and this trend appears poised to continue for many more years. Given the proliferation of mobile computing devices, the size and weight of the mobile computing device has become an important factor in enhancing their adoption, usefulness and attractiveness for users. It is generally very desirable to be able to reduce the size and weight of mobile computing devices to increase their appeal to users. In addition to the expected issues of miniaturization, packaging and design necessary to reduce the size and weight of mobile computing devices, a related issue arises in that heat generated within the mobile computing device becomes a serious design issue due to the density of the components within the smaller enclosures for the computing devices and the higher operating speeds of processors within the computing devices, which results in additional heat generation, and the proliferation of radios (WiFi, Bluetooth, WAN, GPS, etc.) and other heat generating components with mobile computing devices.
An additional issue facing the manufacturers of mobile computing devices is the design and provisioning of the rechargeable batteries used by such devices. Again, as size and weight are important design considerations, the selection and design of batteries for mobile computing devices typically focuses on the energy storage density of the battery, with higher densities desired to enable longer operating times for the devices. Presently, the majority of mobile computing devices employ batteries with a lithium ion (Li-ion) battery chemistry as these batteries provide a good energy storage density.
However Li-ion and most, if not all, other battery chemistries suitable for use in mobile computing devices require carefully managed charging regimes to be employed to maximize the battery's energy storage and the potential operating lifetime (number of possible charge cycles, etc) of the battery and to reduce the possibility of dangerous conditions occurring during charging of the battery which could otherwise put the computing device and/or user at risk of harm.
Accordingly, mobile computing devices typically include charging control circuitry and/or mechanisms which operate to control the charging of their batteries and to prevent unsafe charging. While necessary for safe and appropriate operation of the charging functions of mobile computing devices, these control mechanisms add to the weight of the mobile computing device and also generate waste heat within the mobile computing device.